The invention relates to reflective graphite. The reflective graphite is prepared by preparing a surface nucleated pyrolytic graphite by a chemical vapor deposition technique. The chemical vapor deposition is carried out by the decomposition of low molecular weight hydrocarbon gases at a temperature of 1700.degree.-2200.degree. C. The pyrolytic graphite deposited is annealed at temperatures in excess of 2600.degree. C. and pressures in excess of 5 torr.
U.S. Pat. No. 4,608,192 issued Aug. 28, 1986 describes a process for forming graphite intercalates containing metal charge transfer salts.
U.S. Pat. No. 3,900,540 issued Aug. 19, 1975 describes a method for preparing a thin film of substantially defect-free pyrolytic graphite by vapor deposition on an inert liquid substrate surface followed by separation of the graphite.
U.S. Pat. No. 3,547,676 issued Dec. 15, 1970 describes the preparation of pyrolytic carbon structures by chemical vapor deposition from a mixture of methane and inert gas at a temperature of about 2100.degree. C.
There are several applications where reflective pyrolytic graphite is useful. Reflective graphite can be used for making high temperature reflectors in vacuum equipment and in high temperature heater insulation where the heater is used in inert atmospheres.
The prior art methods of preparing reflective graphite included deposition of metal inclusions in the graphite or deposition of a coating on the graphite to give the desired reflectivity to the product.
More generally it is an object of this invention to provide an improved process for the preparation of reflective graphite by pyrolysis of methane gas or other short chain hydrocarbons wherein the pyrolytic graphite formed on the substrate is annealed at a high temperature and pressure.